1. Technical Field
The present invention relates to a liquid ejecting apparatus and a drive circuit.
2. Related Art
An ink jet printer (liquid ejecting apparatus) which uses a piezoelectric element, for example, a piezo element is known as a printing apparatus which prints an image or a text by ejecting ink. Piezoelectric elements are provided in correspondence with multiple nozzles in a head unit, each of the piezoelectric elements is driven in response to a drive signal, and thereby, a predetermined amount or ink (liquid) is ejected from the nozzle at predetermined timing to form dots. Since the piezoelectric element is electrically a capacitive load like a capacitor, a sufficient current is required to operate the piezoelectric element of each nozzle.
Accordingly, a liquid ejecting apparatus has a configuration in which a source drive signal that is a source signal of a drive signal is amplified by an amplification circuit, and the amplified signal is supplied to a head unit as a drive signal to drive piezoelectric elements. An amplification circuit uses, for example, a method (linear amplification, refer to JP-A-2009-190287) of amplifying current for the source drive signal in class AB amplification or the like. However, power consumption increases and energy efficiency decreases in the linear amplification, and thus, in recent years, a technique or amplifying the source drive signal by switching a pair of transistors including a high-side transistor and a low-side transistor, such as class D amplification (refer to JP-A-2010-114711) is proposed.
Meanwhile, a technique is proposed in which multiple drive signals are generated to increase the number of gradations to be represented, multiple types of drive pulses are included in multiple drive signals, and one drive pulse or multiple drive pulses combined together are applied to a piezoelectric element (refer to JP-A-2005-125804).
Hence, a configuration has been studied in which each of the multiple drive signals is amplified by switching a pair of transistors.
However, in the aforementioned configuration, a relatively large current flows according to turn-on of one of a pair of transistors. Accordingly, when transistors of two or more drive circuits are turned on simultaneously, other circuits are affected by noise or the like caused by the turn-on, and thereby, problems may occur in which reproducibility of a waveform of a drive signal is reduced and print quality is reduced.